Make a copy of OnlineMapsUtils.GetCenterPointAndZoom method into your class, pass the desired screen width and height there, and use that instead of the map width and height.
I think you won't have a problem doing this yourself.

I am trying to use OnlineMapsUtils.GetCenterPointAndZoom to get zoom & center position that fit all markers on screen but I am using a RawImage with TouchForwarder and AdjustScreen and depending on the device resolution, it does not give the expected result. For some mobile device, maps is 3Kx3K or 768x768... Not that not the entire map is displayed on screen, everything is displayed in portrait.

Do you have any suggestion ?

Thank you in advance

Best
AG